1. Field of the Invention
The present invention relates to an in-flight service system that performs switchover to a proxy server unit when a failure occurs in the server unit of a server-client system for use in the in-flight service system.
2. Background Art
A conventional in-flight service system for broadcasting, lighting, and air-conditioning in the cabin of an aircraft uses a server-client system. In the server-client system, a cable network interconnects a server unit for controlling the entire system and performing information delivery service, and a plurality of client units, e.g. operation panel units, for receiving the information from the server unit and performing display and input operations, for example, in proximity to flight attendants or passengers.
When a failure occurs in the server unit during server-client communication in such a system, the client units cannot receive service from the server unit.
To address this problem, the server unit is duplexed such that one is a main server unit normally in operation and the other is a standby server unit. Further, the main server unit and the standby server unit exchange information periodically. Using a monitor timer, the standby server unit detects that information exchange with the main server unit is stopped for a certain period when a failure occurs in the main server unit. In response to that detection, the server function is switched from the main server unit to the standby server unit.
At this time, the standby server unit communicates with all the client units interconnected in the network system so as to inform the client units that the server unit has been changed. Further, the server switchover makes the standby server unit a new server unit, which controls the entire system and distributes information in place of the main server unit.
An example of such a server-client type communication system is disclosed in Patent Literature 1.
However, in such a conventional server-client type communication system, the main server unit having a failure can be switched to the standby server unit only after the following operations. The standby server unit makes communication about the server switchover with all the client units in the network system, and all the client units recognize that the server function is switched to the standby server unit.
For this reason, with a large number of client units, the switchover takes time in some cases. Similarly, when the main server unit recovers from the failure, it also takes time to automatically switch back from the standby server unit to the main server unit.
When the server configuration is duplexed as shown in Patent Literature 1 in the conventional method, units having the same performance and the software having the same function need to be installed. Thus, two server units are necessary.
For a network system to be installed in an aircraft, addition of one server unit to the whole system increases the weight and adversely affects the fuel consumption performance.